Pouch laminating machines as well as roll feed laminating machines for documents are well known. The pouch machines generally comprise a pair of heated platens through which a document enclosed in the pouch is passed between drive rolls to the platens. The pouch is generally a folded over plastic material having thermal properties and adhesives thereon which will bond the plastic to the document to be protected and also the edges of the plastic sheets to each other. The pouch may be within a holder or carrier which is suitably coated to receive any overflow of adhesive material from the pouch and prevent such adhesive material from being deposited on the drive rolls.
Such laminating machines are limited in the thickness of material which may be laminated.
One laminating machine marketed by USI, Inc. of Madison, Conn. provides the ability to accept materials of slightly greater thickness than normal by permitting a small increase in separation of the entrance and exit rolls which does not exceed a dimension which would cause separation of the drive gearing.
This machine comprises a first set of entrance rolls and a second set of exit rolls on either side of upper and lower heating platens. One roll is driven by an electric motor, through gears on the shafts of the rolls and an idler gear the first and second sets of rolls are synchronized. The upper rolls of the first and second sets are journaled in somewhat flexible arms which permit acceptance of materials of a small variation in thickness. However, such variation is limited by the gear teeth. If the gearing between the rolls of each set separates feed of the material is lost.
Other examples of prior art laminating machines are shown in U.S. Pat. Nos. 2,542,901, 3,340,130, 3,711,355, 4,116,749, 4,172,750 and 4,451,320.
The prior art devices discussed above and shown by the aforementioned patents are not suitable for accepting documents of varying thickness, particularly when a thick backing such as foam board is used as a substrate.
Another type of laminating machine is termed a roll laminator. In this type of machine upper and lower supply rolls of plastic film supply film between a first pair of upper and lower laminating rolls which are heated. The film from the supply rolls may be passed over heat shoes or preheat rollers for preheating before entering the nip of the laminating rolls.
In this type of machine the upper rolls of each pair are not driven from the primary power source but only by friction from contact with the material being laminated. An example of a roll laminator is disclosed in U.S. Pat. No. 4,743,334.
This type of machine requires adjustment of a bias on the upper rolls of each pair for pressure between the upper and lower rolls of each pair and/or the permissible thickness of material to be laminated.
Accordingly, the present invention provides a new and improved laminating machine in which the upper roll of a pair of rolls may move upwardly to provide clearance for thick material and auxiliary drive means are provided for driving all rolls in synchronization when the gearing of the rolls of a set of rolls move out of mesh due to the thickness of the material or a substrate therefore.
The invention further provides a laminating machine of the pouch or roll type in which the upper rolls of each pair are driven in synchronism by resilient belts from the lower directly driven rolls. The resilient belts bias the upper rolls downwardly while permitting the upper rolls to move upwardly to accept materials of varying thickness between the upper rolls.
An object of this invention is to provide a laminating machine for laminating a wide range of thickness of documents which is of new and improved construction.
Another object of this invention is to provide a laminating machine for laminating documents within plastic which provides a new and improved structure for accepting documents of varying thickness, and documents on thick substrates.
A further object of this invention is to provide laminating machines in which the upper rolls are driven in synchronism with the lower by a resilient drive means which biases the upper rolls downwardly but permits the upper rolls to move upwardly to accept materials of varying thickness.